Lost PLA Casting With a Little Help From Your Microwave

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[Julia and Mason] have been perfecting their microwave-based lost PLA casting technique over at Hackaday.io. As the name implies, lost PLA is similar to lost wax casting techniques. We’ve covered lost PLA before, but it always involved forges. [Julia and Mason] have moved the entire process over to a pair of microwaves.

Building on the work of the FOSScar project, the pair needed a way to burn the PLA out of a mold with a microwave. The trick is to use a susceptor. Susceptors convert the microwave’s RF energy into thermal energy exactly where it is needed. If you’ve ever nuked a hot pocket, the crisping sleeve is lined with susceptor material. After trying several materials, [Julia and Mason] settled on a mixture of silicon carbide, sugar, water, and alcohol for their susceptor.

The actual technique is pretty simple. A part printed in PLA is coated with susceptor. The part is then placed in a mold made of plaster of paris and perlite. The entire mold is cooked in an unmodified household microwave to burn out the PLA.

A second microwave with a top emitter is used to melt down aluminum, which is then poured into the prepared mold. When the metal cools, the mold is broken away to reveal a part ready to be machined.

We think this is a heck of a lot of work for a single part. Sometimes you really need a metal piece, though. Until metal 3D printing becomes cheap enough for everyone to do at home, this will work pretty well.

Hackaday Links: August 3, 2014

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A ton of people sent in this video of crazy Russians who have taken a microwave, removed the magnetron, taped it to a broom, and turned it on. Don’t try this at home. Or near us.

You know the Google Cardboard kit that’s a real VR headset made of cardboard (and a smart phone)? Google may have gotten their inspiration from Oculus, because every Oculus Rift DK2 ships with a Samsung Galaxy Note 3 inside.

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Ever design a PCB and be disappointed by the quality of the silkscreen? [Paul Allen] has been defining the edges of his PCB labels with the copper layer, and the examples are dramatic. Etching copper is what you actually pay for when you fab a board, so it should come as no surprise that the quality is a little higher.

Dunk tanks are fun, but how about competitive dunk tanks? [Chad] built a dunk tank (really more of a ‘dunk shower’) out of a 2×4 tripod, a garbage can, and a few parts from a the toilet aisle of Home Depot’s plumbing department. Then he built a second. Set up both dunk showers across from each other, give two people a few balls, and see who gets soaked last. Looks fun.

Want a MAME cabinet, but don’t want it taking up room in your house? Build a MAME coffee table! Here’s the reddit thread. Maybe we’re old-fashioned, but we’d rather have a giant NES controller coffee table.

Last week we saw a 16-bobbin rope braiding machine, but odd braiding machines like this aren’t limited to fibers. Here’s a wire twisting machine for making RS422 cables. It only produces a single twisted pair, but that’s really all you need to create a cable. Somebody get some paracord and make some Cat5.

Hackaday Links: July 27, 2014

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Taking apart printers to salvage their motors and rods is a common occurrence in hacker circles, but how about salvaging the electronics? A lot of printers come with WiFi modules, and these can be repurposed as USB WiFi dongles. Tools required? And old printer, 3.3 V regulator, and a USB cable. Couldn’t be simpler.

The Raspberry Pi has a connector for a webcam, and it’s a very good solution if you need a programmable IP webcam with GPIOs. How about four cameras?. This Indiegogo is for a four-port camera connector for the Raspi. Someone has a use for this, we’re sure.

The one flexible funding campaign that isn’t a scam. [Kyle] maintains most of the software defined radio stack for Arch Linux, and he’s looking for some funds to improve his work. Yes, it’s basically a ‘fund my life’ crowdfunding campaign, but you’re funding someone to work full-time on open source software.

Calibration tools for Delta 3D printers. It’s just a few tools that speed up calibration, made for MATLAB and Octave.

[Oona] is doing her usual, ‘lets look at everything radio’ thing again, and has a plan to map microwave relay links. If you’ve ever seen a dish or other highly directional antenna on top of a cell phone tower, you’ve seen this sort of thing before. [Oona] is planning on mapping them by flying a quadcopter around, extracting the video and GPS data, and figuring out where all the other microwave links are.

PowerPoint presentations for the Raspberry Pi and BeagleBone Black. Yes, PowerPoint presentations are the tool of the devil and the leading cause of death for astronauts*, but someone should find this useful.


* Yes, PowerPoint presentations are the leading cause of death for astronauts. The root cause of the Columbia disaster was organizational factors that neglected engineer’s requests to use DOD space assets to inspect the wing, after which they could have been rescued. These are organizational factors were, at least in part, caused by PowerPoint.

Challenger was the same story, and although PowerPoint didn’t exist in 1986, “bulletized thinking” in engineering reports was cited as a major factor in the disaster. If “bulletized thinking” doesn’t perfectly describe PowerPoint, I don’t know what does.

As far as PowerPoint being the leading cause of death for astronauts, 14 died on two shuttles, while a total of 30 astronauts died either in training or in flight.

Smart Microwave Shows You How It’s Done

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Do you still have technical difficulties with your microwave? Never know how long to put that half eaten hot-pocket in for? With the nextWAVE (trademark pending) you don’t need to know! Simply scan the bar code and let the nextWave do its thing — wirelessly!

[Kashev Dalmia], [Dario Aranguiz], [Brady Salz] and [Ahmed Suhyl] just competed in the HackIllinois Hackathon 2014, and their project was this awesome smart microwave. It uses a Spark Core Microcontroller to control the microwave and communicate wirelessly over Wi-Fi. They’ve developed an Android app to allow you to scan bar codes, which are then looked up in a Firebase Database to determine the optimum (crowd sourced) cook time. To make it easy for anyone to use, an app link NFC tag is placed on the microwave for easy installation.

It even automatically opens the door when it’s done — and plays Funky Town! Oh and it also has a Pebble app to show you the time remaining on your food. We think this Raspberry Pi microwave might give it a run for its money though…

[Read more...]

Hackaday Links: April 6, 2014

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Back in September we saw this awesomesauce wristwatch. Well, [Zak] is now kitting it up. Learn more about the current version, or order one. [Thanks Petr]

Home automation is from the future, right? Well at [boltzmann138's] house it’s actually from The Next Generation. His home automation dashboard is based on the LCARS interface; he hit the mark perfectly! Anyone thinking what we’re thinking? This should be entered in the Hackaday Sci-Fi Contest, right? [via Adafruit]

PCB fab can vary greatly depending on board size, number of layers, number of copies, and turn time. PCBShopper will perform a meta-search and let you know what all of your options are. We ran a couple of tests and like what we saw. But we haven’t verified the information is all good so do leave a note about your own experience with the site in the comments below. [via Galactic Studios]

We recently mentioned our own woes about acquiring BeagleBone Black boards. It looks like an authorized clone board is poised to enter the market.

Speaking of the BBB, check out this wireless remote wireless sensor hack which [Chirag Nagpal] is interfacing with the BBB.

We haven’t tried to set up any long-range microwave communications systems. Neither has [Kenneth Finnegan] but that didn’t stop him from giving it a whirl. He’s using Nanobridge M5 hardware to help set up a system for a triathlon happening near him.

One man’s microwave oven is another man’s hobby electronics store

Mads microwave teardown

There are loads of Internet content depicting the usefulness of salvaged innards found in defunct microwave ovens. [Mads Nielsen] is an emerging new vblogger with promising filming skills and intriguing beginner electronics content. He doesn’t bring anything new from the microwave oven to the dinner table, yet this video should be considered a primer for anybody looking to salvage components for their hobby bench. To save some time you can link in at the 5 minute mark when the feast of parts is laid out on the table. The multitude of good usable parts in these microwave ovens rolling out on curbsides, in dumpsters, and cheap at yard sales all over the country is staggering and mostly free for the picking.

The harvest here was: micro switches, X and Y rated mains capacitors, 8 amp fuse, timer control with bell and switches, slow turn geared synchronous 4 watt motor 5 rpm, high voltage capacitor marked 2100 W VAC 0.95 uF, special diodes which aren’t so useful in hobby electronics, light bulb, common mode choke, 20 watt 68 Ohm ceramic wire-wound resistor, AC fan motor with fan and thermostat cutout switches NT101 (normally closed).

All this can be salvaged and more if you find newer discarded units. Our summary continues after the break where you can also watch the video where [Mads] flashes each treasure. His trinkets are rated at 220 V but if you live in a 110 V country such components will be rated for 110 V.

[Read more...]

Current limiter for a MOT welder

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[Mike Worth] wanted the option to run his Microwave Oven Transformer welding rig at less that full power. After being inspired by some of the other MOT hacks we’ve featured he figured there must be a lot of ways to do this. But his searches on the topic didn’t turn up anything. So he just designed and built his own adjustable current limiter for the welder.

At the beginning of his write-up he details what we would call a bootstrap procedure for the welder. Go back and check out his original build post to see that he had been holding the framework for the cores together using clamps. To make the setup more robust he needed to weld them, but this is the only welder he has access to. So he taped some wood shielding over the coils and fired it up.

The current limiter itself is built from a third MOT. Adjustment is made to the cores by changing out the E and I shaped pieces. This allows for current limiting without altering the windings. [Mike] holds it all in place with a couple of bicycle wheel quick connect skewers.

It just goes to show that you should never get rid of a microwave without pulling the transformer. Even if you don’t need a welder wouldn’t you love a high-voltage bug zapper?

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